Bud Dajo (Tausug: Būd Dahu; Spanish: Monte Dajó)
In the photos it looks like the tag might have been Daho, not Dano and that the stem of the "h" wore away. If we consider the Tausug spelling and that the name is pronounced DA-ho, it would not surprise me that someone hearing the name would spell it "Daho". Remember that in Spanish, a "j" is pronounced as an "h".
If this is correct, there were two acknowledged Battles of Bud Dajo, the first in March, 1906 and the second December, 1911.
https://en.wikipedia.org/wiki/First_Battle_of_Bud_Dajo
https://en.wikipedia.org/wiki/Second_Battle_of_Bud_Dajo
There may have been fighting around Lake Danao, but i am not familiar with any battles that name the place specifically, so that seems less likely.